Method and apparatus for providing live view and instant review in an image capture device

ABSTRACT

A method and system for providing instant review of a last image in an image capture device is disclosed. The image capture device includes a viewfinder for displaying a live image and each image of a plurality of previously captured images. The method and system include selecting instant review of the last image captured by the image capture device, determining the status and location of the last image, and providing the last image to the viewfinder for display. Therefore, the image capture device is capable of displaying the last image substantially immediately after the last image has been captured. In another aspect, the image capture device contains an image processing system. In this aspect, the method and system include allowing a user to access a play mode and a review mode while the last image captured undergoes processing by the image processing system.

This is a continuation of application Ser. No. 08/890,896, filed Jul.10, 1997, now U.S. Pat. No. 6,137,534.

FIELD OF THE INVENTION

The present invention relates generally to digital cameras, and moreparticularly to a method and apparatus for providing an instant reviewmode in digital cameras.

BACKGROUND OF THE INVENTION

Most digital cameras today are similar in size to and behave likeconventional point-and-shoot cameras. However, most digital camerasstore digital images in an internal flash memory or on external memorycards and are equipped with a liquid-crystal display (LCD) screen on theback of the camera. Through the use of the LCD, most digital camerasoperate in two modes, live and play. In live mode, the LCD is used as aviewfinder in which the user may view an object or scene before taking apicture. In play mode, the LCD is used as a playback screen for allowingthe user to review previously captured images either individually or inarrays of four, nine, or sixteen images.

When a user wishes to capture an image in live mode, the user sends acapture command, usually by pressing a capture or shutter button. Whenthe image is captured, the image is frozen on the LCD for a relativelylong time while the image is processed and stored in memory. Typically,the image is partially obscured by a “waif” message during processing.Once the camera has finished processing and storing the image, thecamera reverts back to the live mode for capturing further images. Ifthe user desires to view the image just captured, the user must changeto play mode.

Although a user can capture images in live mode, a user cannot obtain anunobstructed view an image that has just been captured without changingfrom live mode to play mode. The user also lacks control over the imagefrozen on the LCD during processing. Similarly, there is no control overthe mode which the camera returns to after processing. Instead, thecamera automatically returns to a live view, forcing the user to switchto play mode to view or perform operations on the last image captured.

Accordingly, what is needed is an improved method and system foraccessing the last image captured by a digital camera. The presentinvention addresses such a need.

SUMMARY OF THE INVENTION

The present invention provides a method and system for providing instantreview of a last image captured in an image capture device. The imagecapture device includes a viewfinder for displaying a live image andeach image of a plurality of previously captured images. The method andsystem comprise allowing a user to select instant review of the lastimage captured by the digital camera. The method and system furthercomprise determining the status and location of the last image andproviding the last image to the viewfinder for display. Therefore, theimage capture device is capable of displaying the last imagesubstantially immediately after the last image has been captured. Inanother aspect, the image capture device contains an image processingsystem. In this aspect, the method and system comprise allowing a userto access a play mode and a review mode while the last image capturedundergoes processing by the image processing system.

According to the system and method disclosed herein, the presentinvention allows a user to view and perform operations on an image veryshortly after the image is captured, thereby increasing overall systemperformance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a digital camera that operates inaccordance with the present invention.

FIG. 2 is a block diagram of one embodiment for the imaging device ofFIG. 1.

FIG. 3 is a block diagram of one embodiment for the computer of FIG. 1.

FIG. 4A is a memory map showing one embodiment of the DynamicRandom-Access-Memory (DRAM).

FIG. 4B is a block diagram illustrating the contents of one of the inputbuffers and the contents of the frame buffer.

FIG. 5 is a block diagram illustrating an enhanced format of still imagefile in accordance with the present invention.

FIG. 6 is a block diagram illustrating the image file generationprocess, which begins when the camera is in capture mode and the userpresses the shutter button to capture an image.

FIG. 7 is a flow chart illustrating one embodiment of the process fordetermining the status of an image.

FIG. 8 is a diagram depicting the top view of one embodiment of adigital camera.

FIG. 9 is a flow chart of one embodiment of a method for providinginstant review.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to an improvement in digital cameras. Thefollowing description is presented to enable one of ordinary skill inthe art to make and use the invention and is provided in the context ofa patent application and its requirements. Various modifications to thepreferred embodiment will be readily apparent to those skilled in theart and the generic principles herein may be applied to otherembodiments. Thus, the present invention is not intended to be limitedto the embodiment shown, but is to be accorded the widest scopeconsistent with the principles and features described herein.

Many conventional digital cameras have two modes: live mode and playmode. In live mode, images are actually captured and the liquid-crystaldisplay (LCD) screen is used as a viewfinder. In play mode, the LCDscreen on the back of the camera can display previously captured images.

In order to switch between modes and control the digital camera in agiven mode, a user interface is typically employed. The user interfacetypically includes a number of buttons or switches for setting thecamera into one of the two modes and for navigating between images inplay mode. For example, a digital camera may include two navigationbuttons labeled “−” and “+”, a mode button, a display button, a zoombutton, a delete button, and a capture or shutter button.

In play mode, the digital camera may begin with a default screendisplaying a full-sized individual image that was previously captured.Other images stored in the camera may be displayed in a backward orforward sequence by pressing the “−” and “+” navigation buttons,respectively. During play mode, the user can also cause four images tobe displayed in a 2×2 array, nine images to be displayed in a 3×3 array,or sixteen images to be displayed in a 4×4 array. The user can then“page” through screens of image arrays or move from image to image inthe arrays. The user may also have the full-sized image displayed of achosen image and can delete the image.

One disadvantage of conventional digital cameras is that when a userwishes to capture an image, the user must first switch from play mode tolive mode. In live mode, the LCD acts as a viewfinder. The user capturesthe image by pressing the capture or shutter button, which typicallycontrols the shutter. The image is then frozen on the LCD while theimage is processed and stored in memory. Processing generally includescompression of the image prior to storage in memory. Therefore, theimage is typically frozen on the LCD screen for a relatively long time,often up to a few seconds. The image frozen on the LCD screen is alsopartially obscured by a “wait” message during processing. In addition,the image displayed on the screen during processing may actually be theimage just prior to the image being processed.

Once the camera has finished processing the image, the cameraautomatically removes the frozen image and reverts back to the live modefor capturing further images. If the user desires to view the image justcaptured, the user must change from live mode to play mode. Only thencan the user view the last images, as well as all previously capturedimages. Once in play mode, the user can also perform operations on theimage, such as deleting the image.

Although a digital camera allows a user to review previously capturedimages and capture new images, one of ordinary skill in the art willreadily recognize that a user cannot obtain an unobstructed view of animage that has just been captured in live mode. Although an image isfrozen on the screen after capture, the image is partially obscured bythe “wait” message. If a user desires an unobstructed view or to performoperations on the last image captured, the user must switch to playmode. There is no control over the image frozen on the LCD duringprocessing. One of ordinary skill in the art will also realize that theuser is unable to control the mode to which the camera returns to afterprocessing. Instead, the camera automatically returns to a live view.

The present invention provides a method and system for providing aninstant review mode which allows instant review of the last imagecaptured in a digital camera. Thus, although the present invention willbe described in terms of instant review of an image, the method andsystem provide rapid review of the image. Although the present inventionwill be described in terms of a digital camera having at least twomodes, live view and instant review, one of ordinary skill in the artwill realize that the present invention is not limited to a digitalcamera having two modes. In a one embodiment, the digital cameraemploying the method and system supports additional modes such as reviewmode and play mode, described below. Finally, although the presentinvention is described in terms of a digital camera, one of ordinaryskill in the art will readily realize that the method and system arefully applicable to any image capture device.

Referring now to FIG. 1, a block diagram of a digital camera 110 isshown for use in accordance with the present invention. Camera 110preferably comprises an imaging device 114, a system bus 116 and acomputer 118. Imaging device 114 is optically coupled to an object 112and electrically coupled via system bus 116 to computer 118. Once aphotographer has focused imaging device 114 on object 112 and, using acapture button or some other means, instructed camera 110 to capture animage of object 112, computer 118 commands imaging device 114 via systembus 116 to capture raw image data representing object 112. The capturedraw image data is transferred over system bus 116 to computer 118 whichperforms various image processing functions on the image data beforestoring it in its internal memory. System bus 116 also passes variousstatus and control signals between imaging device 114 and computer 118.

Referring now to FIG. 2, a block diagram of one embodiment of imagingdevice 114 is shown. Imaging device 114 typically comprises a lens 220having an iris, a filter 222, an image sensor 224, a timing generator226, an analog signal processor (ASP) 228, an analog-to-digital (A/D)converter 230, an interface 232, and one or more motors 234.

In operation, imaging device 114 captures an image of object 112 viareflected light impacting image sensor 224 along optical path 236. Imagesensor 224, which is typically a charged coupled device (CCD),responsively generates a set of raw image data in CCD formatrepresenting the captured image 112. The raw image data is then routedthrough ASP 228, A/D converter 230 and interface 232. Interface 232 hasoutputs for controlling ASP 228, motors 234 and timing generator 226.From interface 232, the raw image data passes over system bus 116 tocomputer 118.

Referring now to FIG. 3, a block diagram of one embodiment for computer118 is shown. System bus 116 provides connection paths between imagingdevice 114, an optional power manager 342, central processing unit (CPU)344, dynamic random-access memory (DRAM) 346, input/output interface(I/O) 348, non-volatile memory 350, and buffers/connector 352. Removablememory 354 connects to system bus 116 via buffers/connector 352.Alternately, camera 110 may be implemented without removable memory 354or buffers/connector 352.

Power manager 342 communicates via line 366 with power supply 356 andcoordinates power management operations for camera 110. CPU 344typically includes a conventional processor device for controlling theoperation of camera 110. In the preferred embodiment, CPU 344 is capableof concurrently running multiple software routines to control thevarious processes of camera 110 within a multithreaded environment. DRAM346 is a contiguous block of dynamic memory which may be selectivelyallocated to various storage functions. LCD controller 390 accesses DRAM346 and transfers processed image data to LCD screen 402 for display.

I/O 348 is an interface device allowing communications to and fromcomputer 118. For example, I/O 348 permits an external host computer(not shown) to connect to and communicate with computer 118. I/O 348also interfaces with a plurality of buttons and/or dials 404, and anoptional status LCD 406, which in addition to the LCD screen 402, arethe hardware elements of the camera's user interface 408.

Non-volatile memory 350, which may typically comprise a conventionalread-only memory or flash memory, stores a set of computer-readableprogram instructions to control the operation of camera 110. Removablememory 354 serves as an additional image data storage area and ispreferably a non-volatile device, readily removable and replaceable by acamera 110 user via buffers/connector 352. Thus, a user who possessesseveral removable memories 354 may replace a full removable memory 354with an empty removable memory 354 to effectively expand thepicture-taking capacity of camera 110. In the preferred embodiment ofthe present invention, removable memory 354 is typically implementedusing a flash disk. Power supply 356 supplies operating power to thevarious components of camera 110. In the preferred embodiment, powersupply 356 provides operating power to a main power bus 362 and also toa secondary power bus 364. The main power bus 362 provides power toimaging device 114, I/O 348, non-volatile memory 350 and removablememory 354. The secondary power bus 364 provides power to power manager342, CPU 344 and DRAM 346.

Power supply 356 is connected to main batteries 358 and also to backupbatteries 360. In the preferred embodiment, a camera 110 user may alsoconnect power supply 356 to an external power source. During normaloperation of power supply 356, the main batteries 358 provide operatingpower to power supply 356 which then provides the operating power tocamera 110 via both main power bus 362 and secondary power bus 364.During a power failure mode in which the main batteries 358 have failed(when their output voltage has fallen below a minimum operationalvoltage level) the backup batteries 360 provide operating power to powersupply 356 which then provides the operating power only to the secondarypower bus 364 of camera 110.

Referring now to FIG. 4A, a memory map showing one embodiment of dynamicrandom-access-memory (DRAM) 346 is shown. In the preferred embodiment,DRAM 346 includes RAM disk 532, a system area 534, and working memory530.

RAM disk 532 is a memory area used for storing raw and compressed imagedata and typically is organized in a sectored format similar to that ofconventional hard disk drives. In the preferred embodiment, RAM disk 532uses a well-known and standardized file system to permit external hostcomputer systems, via I/O 348, to readily recognize and access the datastored on RAM disk 532. System area 534 typically stores data regardingsystem errors (for example, why a system shutdown occurred) for use byCPU 344 upon a restart of computer 118.

Working memory 530 includes various stacks, data structures andvariables used by CPU 344 while executing the software routines usedwithin computer 118. Working memory 530 also includes several inputbuffers 538 for temporarily storing sets of raw image data received fromimaging device 114, and a frame buffer 536 for storing data for displayon the LCD screen 402. In a preferred embodiment, each input buffer 538and the frame buffer 536 are split into two separate buffers, calledping-pong buffers (shown by the dashed lines), to improve the displayspeed of the digital camera and to prevent the tearing of the image inthe display 402. Referring now to FIG. 4B, the contents of one of theinput buffers 538 and the contents of the frame buffer 536 areillustrated. As shown, each input buffer 538 includes an input buffer Aand an input buffer B, and the frame buffer 536 includes a frame bufferA and a frame buffer B. The input buffers A and B alternate between aninput cycle and a processing cycle. During the input cycle, the inputbuffers 538 are filled with raw image data from the image device 114,and during the processing cycle, CPU 344 processes the raw data andtransmits the processed data to the frame buffers 536.

Referring now to FIG. 5, a block diagram of an enhanced format of stillimage file in accordance with the present invention is shown. The imagefile 600 includes a header 602, compressed image data 604, a thumbnailimage 606, a screennail 608, and an image tag field 610. The image file600 may also include a sound file (not shown) if a sound clip has beenattached to the particular image.

The header 602 includes information identifying the particular imagefile and the image represented by the image data 604. The image data 604is the actual data comprising the full-sized captured image incompressed form, preferably in JPEG format. Although the user cantypically choose the resolution mode in which images are captured, oncean image is processed and compressed, the compressed image data 604 isthe high-resolution representation of the image compared to thethumbnail 606 and screennail 608. If the image is captured at aresolution of 640×480 pixels, for example, then the compressed imagedata 604 is typically fifty-to-sixty kilobytes in size.

The thumbnail image 606 is a small, uncompressed low-resolution versionof the image. In a preferred embodiment, the pixel size of thumbnailimage 606 is less than the display size of the LCD screen 402 (e.g.,80×60 pixels), and has a storage size of approximately ten kilobytes.

The screennail image 608 is a medium-resolution version of the image andin a preferred embodiment is also compressed, although compressing thescreennail 608 is optional. Unlike the thumbnail image 606, thescreennail image 608 is display-sized and fills the visible area of theLCD screen 402 when displayed. In one embodiment, the screennail image608 is optional. The screennail image 608 may be optional because theimage sensor 224 is small enough, for example 640×480 pixels in size,that the image data 602 can be very rapidly provided to the LCD screen402. Similarly, the screennail image 608 may be optional where thehardware for the camera 110 is capable of providing the image data 604rapidly enough. In one embodiment in which the screennail image 608 isoptional, the data for the screennail image 608 remains in memoryavailable for display until the image file 600 is completed. In apreferred embodiment, the pixel size of a compressed screennail image608 is preferably 288×216 and requires approximately fifteen kilobytesto store.

The image tag field 610 includes information, preferably in the form oftags, regarding the image represented by the image data 604. Media typetags, for instance, indicate all the media types associated with theimage, such as whether the image is a single image or a panorama image,for example. In certain operating modes, the media type tags are used toselect the type of icon that is displayed in the LCD 402 along side thethumbnail image 606. Besides media tags, the image tag field 610 mayalso include other types of tags for storing additional informationregarding the image and/or the camera 110 itself. For example, a tagcould be used to indicate the settings of the camera 110 at the time theimage was captured, or indicate the identity of the camera manufacturer,for instance. The information in these tags may be accessed through thebuttons on the camera interface 400. The additional information may thenbe displayed either as text in the LCD 402.

The enhanced image file 600 of the present invention is created for eachimage as the user takes pictures while the camera is in capture mode.The enhanced image file 600 is then used to accelerate the userinterface of the digital camera in the review and play mode as follows.When the camera is placed into review mode, the thumbnail images 606contained in the image files 600 are directly displayed on the LCD 402as representations of captured images, which eliminates the need toprocess and decompress the compressed image data 604. And when thecamera is placed into play mode, the screennail image 608 contained inthe image file 600 is first decompressed and displayed on the LCD 402and then optionally updated with the higher-resolution compressed. imagedata 604 as the image data 604 is being decompressed. This featureenables the digital camera to quickly display a full-sized version ofthe captured image in the LCD 402 without the delay incurred by firstdecompressing the higher-resolution JPEG image and resizing it to fit onthe LCD 402. Whether or not to decompress and display the compressedimage data 604 depends on the resolution of the display and theresolution of the screennail images 608.

Referring now to FIG. 6, a block diagram is shown of the image filegeneration process, which begins when the camera is in capture mode andthe user presses the shutter button 418 to capture an image. Asdescribed above, before the user captures an image in capture mode,frames of raw image data are sequentially captured by the imaging device114 at a reduced resolution suitable for LCD screen 402, and each of theframe of the raw image data are stored in the ping-pong buffers (FIG.4B) of an input buffer 538. The live view generation process 612performs gamma correction and color conversion on the raw image data toconvert the data into the YCC format of the LCD screen 402, typicallyYCC 222 format, and then transfers the YCC 222 data for each frame tothe frame buffers 536 for display. The raw image data placed into theinput buffers 538 is also processed for extracting exposure, focus, andwhite balance settings.

Once the user presses the shutter button 418 to capture an image, theraw image data is captured by the image device 114 at a resolution setby the user and the raw image data is stored into an appropriate numberof input buffers 538.

The raw image data is then used to generate an enhanced image file 600for the captured image including the compressed image data 604, thethumbnail 606, and the screennail 608, as shown in FIG. 5.

When generating the thumbnail and screennail images 606 and 608, thepresent invention takes advantage of the fact that the YCC data in theframe buffers 536 has already been processed by the live view generationprocess 612 and stored at the reduced resolution of the LCD screen 402.Since the thumbnail and screennail images 606 and 608 are also intendedto be lower-resolution representations of the captured image, thepreviously processed YCC data in the frame buffers 536 is used togenerate the thumbnail 606 and screennail 608 directly, rather thanusing the raw image data stored in the input buffers 538.

To generate the screennail image 608, the YCC data in the frame buffers536 is converted from YCC 222 format into YCC 422 format and compressedby a conversion and compression process 614. To generate the thumbnailimage 606, the YCC data in the frame buffers 536 is converted from theYCC 222 format into YCC 422 format and then resized by a conversion andresizing process 616. During the conversion and resizing process 616,the thumbnail image 606 may be resized by averaging in which a block ofpixel values from the YCC 422 data are averaged to represent one pixelvalue of the thumbnail image 606, and/or by sub-sampling the YCC 422data in which only a certain number pixels in a block are used torepresent one pixel in the thumbnail image 606.

Referring now to FIGS. 4A, 5 and 6, after the thumbnail image 606 andthe screennail 608 are generated, they are stored in working memory 530until the compressed image data 604 is generated. The compressed imagedata 604 may be generated either before or after the thumbnail andscreennail images 606 and 608. However, in a preferred embodiment, thecompressed image data 604 is generated after the thumbnail andscreennail images 606 and 608 are generated using a background spoolingprocess 618. In an alternative embodiment, the thumbnail image 606 andthe screennail 608 may be generated by the background spooling process618 along with the compressed image data 604.

In another preferred embodiment, the thumbnail image 606 and thescreennail 608 may be generated using a two-stage live view generator612. In the first stage, the live view generator 612 provides images tothe frame buffer 536 for display as described above. When the usercaptures an image, the raw image data from the imaging device iscompressed due to higher quality before being stored in the inputbuffers 538, and the live view generator 612 switches to the secondstage. In this stage, the live view generator 612 decompresses thecompressed raw image data and processes the data into both YCC 222 dataand YCC 422 data. The live view generator 612 may then transfer the YCC422 data to the frame buffer 536 for display, and generate the thumbnailimage 606 and the screennail 608 from the YCC 422 data.

The background spooling process 618 preferably includes RAM spoolers 1and 2 (620), removable memory spoolers 1 and 2 (624), and an imageprocessing and compression process (IPC) 622. Processes 620, 622 and 624are preferably implemented as background processes on CPU 344 and maytherefore run in parallel with other processes. As used herein, aspooler is a process that transfers data from one process or device to asecond process or device. The primary purpose of the background spoolingprocess 618 is to move data out of the input buffers 538 as fast aspossible in order to free the input buffers 538 to capture anotherimage. After the data is moved, the data is processed in the background.This allows the next image to be captured before the previous image isprocessed and compressed, which increases the capture rate of thedigital camera.

In operation, after the user has captured an image, control of the rawimage data in the input buffers 538 is transferred to RAM spooler 1(620) if the RAM disk 532 is not full. If the RAM spooler 1 (620)obtains control of the raw image data, then the RAM spooler 1 (620)transfers the raw image data to the RAM disk 532. Alternatively, if theRAM disk 532 is full, then control of the raw image data is transferredto the IPC 622 where the data is processed and compressed to generatethe compressed image data 604 (FIG. 5).

In the case where the raw image data has been transferred to the RAMdisk 532, the removable memory spooler 1 (624) may then access the rawimage data from the RAM disk 532 and transfer it to the removable memory354. Once the raw image data is transferred to the removable memory 354,the IPC 622 accesses the raw image data and processes the raw image datato generate the compressed image data 604. Alternatively, if theremovable memory 354 is full or is not present, then the removablememory spooler 1 (624) may provide the raw image data directly to theIPC 622 for generation of the compressed image data 604.

After the compressed image data 604 is generated, the IPC 622 mayprovide the compressed image data 604 to the RAM spooler 2 (620). Thecompressed image data 604 is then combined with the thumbnail 606 andthe screennail 608 to generate the enhanced image data file (FIG. 5),and the RAM spooler 2 (620) transfers the compressed image data file 600to the RAM disk 532. Once the image data file 600 is written to RAM disk532, the removable memory spooler 2 (624) may then access the image datafile 600 and write the image data file 600 onto the removable memory354. If the removable memory 354 is not inserted, the image data file600 remains on the RAM disk 532. It should be noted that in analternative embodiment, the digital camera may be implemented without aRAM disk 532, in which case the image data would be spooled to and fromthe removable memory 354.

Because image data is moved between different components duringbackground spooling, the computer 118 has a mechanism for keeping trackof and accessing the image data. For example, in review mode, thedigital camera 110 may be required to display the thumbnail image 606 ofa particular image on the LCD screen 402. Similarly, in play mode, thescreennail image 608 of a particular image may be required for displayon the LCD screen 402. Processing of the image may, however, beincomplete when the digital camera 110 is required to display the imageon the LCD screen 402. As a result, the computer 118 must be capable ofaccessing the image at any point during processing.

FIG. 7 depicts a flow chart of a method 700 for accessing the image forvarious purposes, such as use in review or play mode, at any time duringor after the image data is processed. First, the status of the image isdetermined via step 712. In one embodiment, determining the status ofthe image includes not only how far along in processing the image is,but also where the image is located. For example, when the image data isspooled as discussed above, the image may be unprocessed and in theinput buffer 538, unprocessed and in the RAM disk 532, or processed andin the RAM disk 532. If image processing is complete, creation of thethumbnail image 606 and screennail image 608 is already completed. In anembodiment where the thumbnail image 606 and screennail image 608 aregenerated from data in the frame buffer 536, the processing may beconsidered to be complete because the thumbnail image 606 and screennailimage 608 are available.

If the thumbnail image 606 and screennail image 608 are completed, thenthe image data requested is accessed. If a thumbnail image 606 wasrequested, for example for use in review mode, the thumbnail image 606is retrieved and resized via step 720. If the screennail 608 wasrequested, for example for use in play mode, then via step 722, thescreennail 608 is retrieved, decompressed, and resized. Either thethumbnail image 606 or the screennail 608 are then displayed on the LCDscreen 402. The last image may also be retrieved once processing of theimage is complete. If the full image is required for display, the imageis decompressed, resized, and displayed via step 724. As a result, thedigital camera 110 can provide a high resolution update of thescreennail 608 displayed on the LCD screen 402.

If processing of the image is not complete, then the thumbnail image 606and screennail 608 are generated via 714. If the thumbnail image 606 wasrequested, then the thumbnail image 606 is resized and displayed viastep 716. Similarly, if the screennail is requested, the screennail 608is decompressed and displayed via step 718. Consequently, the user canview the image even though processing is incomplete.

To further illustrate the method and system in accordance with thepresent invention, refer now to FIG. 8, depicting the top view 430 of aportion of one embodiment of the digital camera 110 in accordance withthe method and system. The camera 110 includes a capture or shutterbutton 404 and a sound button 414. A user captures an image bydepressing the shutter button 404.

The top view 430 also depicts a slide/lock switch 421 for accessing aninstant review mode in accordance with the method and system. The switch421 is shown as having three positions: live 422, instant review 423,and lock 424. When in the live position 422, the digital camera 110 willallow capture of an image by depressing shutter button 404. Because ofthe spooling of data, described above, image capture appears extremelyfast to a user. Thus, when the user depresses the shutter button 404,there is a brief response indicating the image has been captured, suchas a flicker, a sound, or a very brief freezing of the image on the LCDscreen 402. The camera 110 then quickly returns to live view. Typically,the user need not wait for the image to be processed before the digitalcamera 110 reverts to live mode. The image is, therefore, not frozen fora relatively long time on the LCD 402, and no “wait” message isrequired.

When the user pushes the switch 421 into the instant review position423, the digital camera is placed into instant review mode and the useris given the opportunity to view the last image captured. The camera 110remains in instant review mode until the user returns the switch 421 tothe live position 422. In a preferred embodiment, the switch 421 is aspring loaded switch for which the default position is the live position422. Thus, the camera 100 remains in instant review mode only as long asthe user holds the switch 421 in the instant review position 423. Whenthe user releases the switch 421, the digital camera 110 reverts to livemode. Once the camera 110 returns to live mode, the user can thencapture another image. By holding and releasing the switch 421 betweenthe instant review position 423 and the live position 422, the user cantoggle between the live view and instant review of the last imagecaptured. While in instant review mode, the user may perform certainoperations on the last image captured in addition to viewing the lastimage captured. For example, the user will be able to add sound to thelast image captured through the use of the sound button 414. When theuser captures a second image, the second image will be placed on the LCDscreen 402 until the user either exits instant review mode by releasingthe switch 421 or presses the shutter button 404, as discussed morefully below.

To add sound to an image, a user presses the sound button 414 to beginrecording. To finish recording, the user presses the sound button 414again. In a preferred embodiment, the sound clip can be recorded eitherbefore or after the image to be annotated is captured. In addition, auser can add a recorded sound clip to any previously captured image, notjust the last image captured.

FIG. 9 depicts a method 800 for providing instant review mode inaccordance with the method and system. When the switch 421 is placed inthe instant review position 423, the method 800 is invoked. First, it isdetermined if the frame buffer 536 still contains the data for the lastimage taken via step 810. If the image data is available in the framebuffer 536, then this data is provided to the LCD screen 402 via step812. In one embodiment, the last image will be retained in the framebuffer 536 until the memory is required. If, however, the image data isno longer in the frame buffer 536, for example because the memory framebuffer 536 was required for other purposes, then the status of the imageis determined via step 814. Step 814 of the method 800 is analogous tothe step 712 of the method 700.

If the image processing is complete, then the screennail image 608 forthe last image is retrieved, decompressed, and displayed via step 816.If the last image was very recently captured and the processing is notcomplete, then the screennail image 608 is generated via step 818. Thescreennail image 608 is then decompressed and displayed via step 820. Inone embodiment, the thumbnail image 606 and screennail image 608 arecreated prior to spooling of the image data. As a result, steps 818 and820 are not required in such an embodiment.

The user can also lock the digital camera 110 into instant review modeby placing the switch 421 in the lock position 424. When the digitalcamera 110 is first locked in instant review mode, the LCD screen 402maintains a live view if there is no previously captured image.Otherwise, the last image captured will be placed on the LCD screen 402.The last image captured remains on the LCD screen 402 until the usereither exits instant review mode by releasing the switch 421 or bypressing a shutter button 404. A user captures an image by depressingthe shutter button 404. In one embodiment, the shutter button 404 hastwo positions: a first position, where the button is slightly depressed,and a second position where the button 404 is further depressed.Depressing the shutter button 404 to the first position causes a liveimage to appear on the LCD screen 402, allowing the LCD screen 402 to beused as a viewfinder. Depressing the shutter button 404 to the secondposition causes an image to be captured.

When the user pushes the shutter button 404 to the second position, thecamera 110 provides a response indicating the image has been captured.Because of the spooling of the image data, the image is not frozen onthe LCD screen 402 during image processing. Instead, the camera 110provides a brief response indicating the image has been captured.Instant review mode then causes the image to be placed on the LCD screen402. In this case, instant review mode is provided using a methodsimilar to the method 800 of FIG. 9. However, because the image was justcaptured, the image data should still be in the frame buffer 536. As aresult, this data is generally displayed on the LCD screen 402.

In order to return to a live view, the user releases the shutter buttonthen presses the shutter button 404 into the first position. As aresult, the last image is removed from the LCD screen 402 and replacedwith a live view. In one embodiment, if the user then releases theshutter button, the last image is not placed on the screen again.However, in another embodiment, when the user releases the shutterbutton 404 from the first position, the last image is again displayed onthe LCD screen 402. If available, the image data from the frame buffer536 is used to display the image. If, however, the data was removed fromthe frame buffer, then the screennail image 608 from the last image isused. Thus, steps 814 through 820 of the method 800 would employed.

In one embodiment, if the digital camera 110 retains this image on theLCD screen 402 for a long enough interval, the digital camera 110 willupdate the screennail image 608 using the full resolution image. In sucha case, the digital camera 110 would also retrieve, decompress anddisplay the corresponding compressed image data 602. While in instantreview mode, the user can perform operations on the image beingreviewed, such as annotating the image with sound, as in the review andplay modes.

In order to be able to capture another image, the user again depressesthe shutter button 404 to the second position. When the user capturesthe second image, the second image will be placed on the LCD screen 402until the user again releases and presses the shutter button 404 intothe first position. In order to exit instant review mode, the usersimply moves the switch 421 from the lock position 424 to the liveposition 422.

Although the instant review mode is described as being accessed througha switch 421, nothing prevents instant review mode from being accessedin another fashion. In another embodiment, instant review mode may beaccessed through software, for example by choosing an appropriate icondisplayed on the LCD 402. In such an embodiment, however, switchingbetween live mode and instant review mode may be made more difficult bythe numbers of commands through which a user may need to scroll toaccess the instant review mode icon. In addition, in an embodiment inwhich the user accesses instant review mode through software, once auser leaves instant review mode through the software command, the lastimage may not be recalled onto the screen by switching back to instantreview mode. Although the embodiment discussed above retains the lastimage on the LCD screen 402 until the shutter button 404 is released andpressed into a first position, nothing prevents the removal of the lastimage for another reason. For example, in an alternate embodiment, thelast image may be retained on the LCD screen for a given time interval.Finally, although reference is made to an instant review mode, the modeprovides rapid review of the last image captured.

A method and system have been disclosed for providing an instant reviewmode in a digital camera. Although the present invention has beendescribed in accordance with the embodiments shown, one of ordinaryskill in the art will readily recognize that there could be variationsto the embodiments and those variations would be within the spirit andscope of the present invention. Accordingly, many modifications may bemade by one of ordinary skill in the art without departing from thespirit and scope of the appended claims.

What is claimed is:
 1. A method for providing instant review of a lastimage captured by an image capture device, the image capture deviceincluding a viewfinder for displaying a live image and each image of aplurality of captured images, and a buffer for storing an image fordisplay on the viewfinder, wherein the image capture device furtherincludes an image processing system, wherein the image processing systemfurther provides a plurality of screennail images corresponding to theplurality of images, the method comprising the steps of: (a) allowing auser to select instant review of a last image captured by the imagecapture device; (b) determining a status and location of the last image;and and wherein step (b) further comprises the step of: (b1) determiningif the last image is stored in the buffer; and (b2) checking a status ofthe last image in the image processing system if the last image is notstored in the buffer, and wherein step (b2) further comprises the stepof: (b2i) determining if the screennail image corresponding to the lastimage has been generated; (c) providing the last image to the viewfinderfor display to allow the last image to be edited before image processingfor the last image is completed, wherein editing includes allowing auser to add supplemental data to the image; wherein the image capturedevice is capable of displaying the last image substantially immediatelyafter the last image has been captured; and wherein step (c) furthercomprises the steps of: (c1) providing the last image from the buffer tothe viewfinder if the last image is stored in the buffer; (c2)retrieving and resizing the screennail image and providing thescreennail image to the viewfinder if the screennail image correspondingto the last image has been generated.
 2. The method of claim 1 whereinstep (c2) further comprises the steps of: (c2i) creating the screennailimage if the screennail image has not been generated.
 3. The method ofclaim 2 wherein step (a) further comprises the step of: (a1) providing aswitch for allowing the user to access the instant review mode.
 4. Themethod of claim 3 wherein step the switch further comprises a lockedposition, the locked position for locking the image capture device inthe instant review mode, wherein the image capture device furtherincludes a shutter button, and wherein step (a1) further comprises thestep of: (a1i) allowing the user to place the switch in the lockedposition; and wherein step (a) further comprises the step of: (a2)allowing the user to depress the shutter button to capture a next image,wherein the next image becomes the last image.
 5. The method of claim 4wherein the shutter button further includes a first position and asecond position, the second position for capturing an image, where step(a2) further comprises the step of: (a2) allowing the user to depressthe shutter button to the second position to capture the last image; themethod further comprising the step of: (d) removing the last image fromthe viewfinder if the shutter button is released and depressed into thefirst position after capture of the last image.
 6. The method of claim 5further comprising the step of: (e) providing the last image to theviewfinder if the shutter button is again released from the firstposition.
 7. The method of claim 6 wherein the image capture device is adigital camera.
 8. The method of claim 4 further comprising the step of:(d) removing the last image from the viewfinder when a predeterminedtime interval has elapsed.
 9. The method of claim 2 wherein step (a)further comprises the step of: (a1) accessing an instant review mode viaan icon displayed on the viewfinder.
 10. A method for providing instantreview of a last image captured by an image capture device, the imagecapture device including a viewfinder for displaying a live image andeach image of a plurality of captured images, wherein the image capturedevice further includes an image processing system for processing eachof the plurality of previously captured images, wherein the imageprocessing system further provides a plurality of screennail imagescorresponding to the plurality of images, the method comprising thesteps of: (a) allowing a user to select instant review of a last imagecaptured by the image capture device; (b) determining a status andlocation of the last image, wherein step (b) further comprises the stepof: (b1) determining if a particular screennail image has beengenerated; (c) providing the last image to the viewfinder for display toallow the last image to be edited before image processing for the lastimage is completed, wherein editing includes allowing a user to addsupplemental data to the image; and (d) allowing a user to access a playmode and a review mode while the last image captured undergoesprocessing by the image processing system, and wherein step (d) furthercomprises the step of: (d1) retrieving, resizing, and providing theparticular screennail image to the viewfinder if play mode has beenaccessed; wherein the image capture device is capable of displaying thelast image substantially immediately after the last image has beencaptured.
 11. The method of claim 10 wherein the image processing systemfurther provides a plurality of thumbnail images corresponding to theplurality of previously captured images, wherein step (b) furthercomprises the step of: (b2) determining whether a portion of theplurality of thumbnail images have been generated; and wherein step (d)further comprises the step of: (d2) retrieving, resizing, and providingthe portion of the plurality of thumbnail images to the viewfinder ifreview mode has been accessed.
 12. The method of claim 11 wherein step(d1) further comprises the steps of: (d1i) creating the screennail imageif the screennail image has not been generated.
 13. The method of claim12 wherein step (d2) further comprises the steps of: (d1i) creating theportion of the plurality of thumbnail images if a thumbnail image of theportion of the plurality of thumbnail images has not been generated. 14.The method of claim 13 wherein the image capture device is a digitalcamera.
 15. An image capture device for providing instant review of alast image captured by the image capture device comprising: a viewfinderfor displaying a live image and each image of a plurality of previouslycaptured images; selection means coupled with the viewfinder forselecting instant review of the last image captured by the image capturedevice; means coupled to the selection means for determining the statusand location of the last image, wherein the determining means furthercomprise: buffer determining means for determining if the last image isstored in a buffer; means for checking a status of the last image in theimage processing system if the last image is not stored in the buffer;screennail determining means for determining if a screennail image hasbeen generated; and means coupled to the determining means for providingthe last image to the viewfinder for display to allow the last image tobe edited before image processing for the last image is completed,wherein editing includes allowing a user to add supplemental data to theimage, and wherein the last image providing means further comprise:means coupled to the buffer for providing the last image from the bufferto the viewfinder if the last image is stored in the buffer; means forretrieving, decompressing, and resizing the screennail image if thescreennail image has been generated; and means coupled to the retrievingmeans for providing the screennail image to the viewfinder; and thebuffer coupled to the viewfinder for storing an image for display on theviewfinder; an image processing system coupled to the viewfinder forproviding a plurality of screennail images corresponding to theplurality of images; wherein the image capture device is capable ofdisplaying the last image substantially immediately after the last imagehas been captured.
 16. The image capture device of claim 15 wherein thelast image providing means further comprise: means coupled to the meansfor providing the screennail to the viewfinder for creating thescreennail corresponding if the screennail image has not been generated.17. The image capture device of claim 16, wherein the selection meansfurther comprise: a switch for accessing an instant review mode.
 18. Theimage capture device of claim 17 wherein the switch further comprises: alocked position, the locked position for locking the image capturedevice in the instant review mode; the image capture device furthercomprising: a shutter button coupled to the switch for capturing animage and activating the instant review mode.
 19. The image capturedevice of claim 18 wherein the shutter button further comprises: a firstposition and a second position, the second position for capturing animage; and wherein the image capture device further comprises: meanscoupled to the viewfinder for removing the last image from theviewfinder if the shutter button is released and depressed into thefirst position.
 20. The image capture device of claim 19 furthercomprising: means coupled to the shutter button for providing the lastimage to the viewfinder it the shutter button is released from the firstposition.
 21. The image capture device of claim 18 further comprising:means coupled to the viewfinder for removing the last image from theviewfinder when a predetermined time interval has elapsed.
 22. The imagecapture device of claim 18 wherein the selection means further comprise:means for accessing an instant review mode via an icon displayed on theviewfinder.
 23. The image capture device of claim 22 wherein theviewfinder further comprises a LCD screen.
 24. The image capture deviceof claim 23 further comprising: means for annotating the last imagecaptured.
 25. The image capture device of claim 24 wherein theannotating means further comprise: means for adding sound to the lastimage captured.
 26. The image capture device of claim 25 wherein theimage capture device is a digital camera.
 27. An image capture devicefor providing instant review of a last image captured by the imagecapture device comprising: a viewfinder for displaying a live image andeach image of a plurality of previously captured images; selection meanscoupled with the viewfinder for selecting instant review of the lastimage captured by the image capture device; means coupled to theselection means for determining the status and location of the lastimage; and means coupled to the determining means for providing the lastimage to the viewfinder for display to allow the last image to be editedbefore image processing for the last image is completed, wherein editingincludes allowing a user to add supplemental data to the image; an imageprocessing system for processing each of the plurality of previouslycaptured images, the image processing system allowing a user to access aplay mode and a review mode while the last image captured undergoesprocessing by the image processing system; wherein the image processingsystem further provides a plurality of screennail images correspondingto the plurality of images, wherein the status and location determiningmeans further comprise: means for determining if a particular screennailimage has been generated; the system further comprising: means forretrieving, resizing, and providing the particular screennail image tothe viewfinder if the play mode has been accessed; and wherein the imagecapture device is capable of displaying the last image substantiallyimmediately after the last image has been captured.
 28. The system ofclaim 27 wherein the image processing system further provides aplurality of thumbnail images corresponding to the plurality ofpreviously captured images, the status and location determining meansfurther comprise: means for determining whether a portion of theplurality of thumbnail images have been generated; and the systemfurther comprising: means for retrieving, resizing, and providing theportion of the plurality of thumbnail images to the viewfinder if reviewmode has been accessed.
 29. The system of claim 28 wherein thescreennail retrieving means further comprise: means for creating thescreennail image if the screennail image has not been generated.
 30. Thesystem of claim 29 wherein the thumbnail retrieving means furthercomprise: means for creating the portion of the plurality of thumbnailimages if a thumbnail image of the potion of the plurality of thumbnailimages has not been generated.
 31. The system of claim 30 wherein theimage capture device is a digital camera.